Elevator door safety lock



March 1954 M. c. HOLMSTROM 71,531

ELEVATOR DOOR SAFETY LOCK Filed May 16, 1952 2 Sheets-Sheet l g I 6, 5 kZ g E E 47 R E :1 56? 1: 53 z i 35 1554 6.0; 4D 0 Q Z9 P Z 50 ,29

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F "iVVENTbR 15 Z 7 Z4 Maw/f2 o/mszram ATTORNEY March 9, 1954 M. c.HOLMSTROM 2,671,531

ELEVATOR DOOR SAFETY LOCK Filed May 16, 1952 2 Sheets-Sheet 2 i a 30 20INVENTOR 1 J' Maurvzz C. fio/mszr'om 4 d F. 7 mamm' Patented Mar. 9,1954 UNITED STATES PATENT OFFICE ELEVATOR DOOR SAFETY LOCK Mauritz O.Hohnstrom, St. Paul, Minn.

Application May 16, 1952, Serial No. 288,163

12 Claims. 1

This invention relates to an improvement in an elevator door safety lockand deals particularly with a lock for-an elevator of the type employingvertically slidable doors.

Various types of safety locks have been employed for use onelevators ofthe type most commonly used as freight elevators. These safety locks aredesigned to prevent opening of the elevator doors at any time exceptwhen the elevator is level with that particular door opening. In view ofthe fact that it is sometimes desirable to be able to open the doorswhen the elevator is not level with the floor, the persons using theelevator remove these safety looks or render them useless. The presentdevice is designed to render locks of this type more foolproof and toprevent those using the elevator from tampering with the safety devicesand destroying their usefulness.

A feature of the present invention resides in the provision of anelevator lock employing an elongated rod fastened for movement with oneof the doors and extending through the housing of the look. When thisrod is in place the door can not be opened unless the elevator is levelwith the door opening. If the rod is removed the elevator circuit isbroken so that theelevator can not be used. As a result the device isrelatively fool-proof and can not readily be rendered useless withoutconsiderable difficulty.

A further feature of the present invention resides in the provision ofan elevator. safety lock which is provided with a locking arm providedwith a grooved end. This grooved end is designed toaccommodate an end ofthe latch bar of the elevator door. When the latch bar is in latchingposition the locking arm is pivoted in a manner to close a circuitswitch so that the elevator may be operated. When the locking arm is inthis position the latch bar is held from vertical movement. As a resultthe door can not be opened while the circuit to the elevator is closed.

A further feature of the present invention lies in the provision of ameans for holding the looking arm in circuit breaking position. As theelevator door is opened a rod secured to the door enters the groove ofthe locking arm and prevents this locking arm from pivoting intoposition to close the elevator circuit. Thus the operator of theelevator can not render the elevator operative while the door is openby'manually swinging the locking arm into circuit closing position andwedging the arm in this position to hold the circuit closed.

.An important feature of the present invention liesin the provision of ameans for holding the locking arm in circuit breaking position while theelevator door is open and in providing an additional means for breakingthe circuit in the event the locking arm holding device is removed. Ifthe member which enters the groove of the locking arm to hold it incircuit breaking position is detached and removed, an additional circuitbreaking switch is actuated to break the elevator circuit.

These and other objects and novel features of the present invention willbe more clearly and fully set forth in the following specification andclaims.

In the drawings forming a part of the specification:

Figure 1 is an elevation view of a portion of a pair of verticallyslidable elevator doors, the elevator door frame, and the safety lockmechanism.

Figure 2 is a sectional view through a portion of the elevator door andframe, the position of the section being indicated by the line 2--2 ofFigure 1. 1

Figure 3 is a perspective view of the lock housing, the operatingmechanism having been removed therefrom.

Figure 4 is a sectional view through the safety lock, the position ofthe section being indicated by the line. 4-4 of Figure 1.

Figure 5 is an elevation view of the safety lock mechanism, the housingcover plate having been removed.

Figure 6 is a sectional view similar to Figure 4 showing the lock in adifferent position.

Figure 7 is an elevation view of the lock with the housing coverremoved, showing a modified form of construction.

Figure 8 is a sectional view through the apparatus, the position of thesection being indicated by the line 88 of Figure 5.

The elevator door lock includes a supporting housing which is indicatedin general by the numeral II}. This housing 10 is secured by bolts orother suitable means to the door guides H which guide the elevator doorsin their vertical movement. Alternatively the housing l0 could bemounted upon the shaft wall I2 forming a part of the door frame, or inany other suitable manner.

The elevator door opening is normally closed by a pair of verticallyslidable doors I3 and M which slide in the guides ll. Each door issubstantially half the height of the door opening so as to close theopening when the upper door [3 ,is lowered and the lower door [4 israised. Means are provided, not illustrated, for connecting the doors I3and I4 so that the doors will open and close in unison. Sucharrangements are conventional in the art.

As illustrated in Figure 2 of the drawings, the guides H are providedwith an inwardly facing channel l5 which is designed to accommodate anoutwardly turned flange l6 of an angle member I! mounted at the sideedge of each door. The channel l5 slidably supports the flange It topermit free vertical movement of the doors.

In order to hold the doors closed, a pair of latch bars I9 are provided,one of which is illustrated in the drawings. In usual types ofconstruction the two latch bars are connected to a lever which movesboth latch bars into projected or retracted position simultaneously.When the latch bars I9 are projected laterally a right angularlyextending extremity engages over a wedge shaped lug 2| on the casing Hito hold the door M from lowering. When the projecting end 20 of thelatch bar I9 is in the position illustrated in Figure 5 of the drawings,this extremity 20 will strike the upperend of the lug 2| upon slightdownward movement of the door l4, the lug arresting further movement ofthe door.

7 It is usual practice to provide a member such as the lug 2| at eachside of the door opening so that each of the two latch bars l9 engages acorresponding shoulder and locks the door [4 from opening. Obviously thesafety look A may be used on either. or both sides of the door opening.In the event the safety lock is mounted on the opposite side of the dooropening from that illustrated in the drawings, the parts arecorrespondingly reversed.

The housing I0 is illustrated in Figure 3 of the drawings, the operatingparts of the mechanism being omitted. As illustrated in Figure 3, thehousing body includes a backing plate 22 from whichprojects asubstantially L-shaped wall 23. The outer side of the housing isprovided with an elongated vertically extending chamber 24 from whichthe wedge shaped projection 2| extends. A short partition wall 25separates the. elongated chamber 24 from the shorter chamber 26. Anelongated tubular housing 21 is secured to the upper wall 29 of thehousing, the tubular enclosure being illustrated in Figures 1, 4 and 5of the drawings.

A locking. arm 30 is pivotally supported at 3| to the base wall 22 ofthe housing I0. This locking arm 3|] is of sufficient length to extendinto close proximity with the-upper extremity of the wedge shaped lug2|. The lower wall 32 of the shorter chamber 26 is apertured at 33 sothat the locking arm 30 may extend through this wall 32. The upper endof the adjoining wall 34 of the longer chamber 24 is also apertured at35 to accommodate a lateral extension 36 on the locking arm 33 andintegral therewith.

The locking'arm 30 is provided with a forwardly extending enlargement 31which is slotted or bifurcated as indicated at 39. The slot walls arepreferably curved so that the locking arm 30 may pivot withinpretermined limits while still accommodating the angularly turnedextremity 20 of the latch bar IS. The lateral extension 33 is aperturedas indicated at 40 for a purpose which will be later described indetail.

A lever arm 4| is pivotally supported in the elongated chamber 24 of thehousing I0 by means ofa pivot 42 which extends through the outer wall43. of the chamber 24 and through the partition wall 25. This leverv arm4| is pivotally connected at 43 to a lever arm continuation 44 which isbifurcated at its outer end 45 to support a roller 46. A pivot 41extends through the bifurcated ends of the extension 44 to rotatablysupport the roller 45. The pivot 43 is only employed for providing aninitial adjustment of the angularity between the lever 4| and theextension 44. Once the position of the extension 44 relative to thelever 4| is determined a pin or key 49 may extend through the lever andthe extension to hold these elements from relative pivotal movement. Inother words, once the adjustment between these parts is made, the lever4| and its extension 44 form an integral unit.

A latch bolt 50 is slidably supported by the housing |0for movementtoward or away from the base wall 22. Guides 5| illustrated in Figure 3of the drawings guide the latch bolt in its sliding movement. The latchbolt 50 is provided with a bifurcated end 53 which is pivotallyconnected at 54 to the lever 4|.. Sufficient play'is provided betweenthe latch bolt and the lever to compensate for the varying angularitybetween these parts.

The latch bolt 50 is of proper proportions to extend into the aperture40 on the locking arm 34.- Thus when the lever 4| is in the positionillustrated in Figure 4 of the drawingsthe latch bolt extends into thelockingarm 30 and holds this locking arm from pivotalmovement. The lever4| is actuated by a cam such as the cam 55 in Figure 6 of the drawings.When the roller 46 engages the cam 55, the lever 4| is pivoted in acounter-clockwise direction as viewed in Figures 4 and 6. When thuspivoted, the latch bolt 50 is withdrawn from the aperture 40 of thelocking arm 30. so that the locking arm is free to pivot.

A spring 55 is interposed between the lever 4| and the base plate 22 ofthe. housing l0 so as to normally urge the latch bolt 50 into thelocking arm aperture 40. The spring 55 also tends to. urge the roller 46into position for engagement" with a cam such as 55.

The upper wall 29 and lower. wall. 32 .of. the

smaller chamber 26 are provided with. key hole shaped apertures 51 and59 respectively. These apertures are substantially axially aligned withthe tubular enclosure 2T mounted upon the upper wall 29 of thehousing:An elongated rod' 50' havinga radially extending fin or flange: 3|thereupon is slidably supported by. the openings .51 and 59.

30 can not rotate.

A bracket 54'is secured to the lower door I4 and is provided with abearing 55"at its' outer extremity through which the rod 50 extends:

The lower end of therod 60 is threaded to accomin retracted position.

A switch 56-is mounted'upon the partition wall 25. of the housing l0 andincludes an. operating The upper extremity of the rod 50 is providedwith a disc shaped flange 52 which forms a bearing for the upper end ofthe rodlil-w within the tubular enclosure 21' and which prevents the rodfrom being pulled downwardly out ofthe housing. The flange or fin 5|terminates at 63 in spaced relation to the lower end ofthe" rod 50.However, the proportions are such that the pin or flange 6| is at alltimes engaged in at least one of the openings 51 or 59-50 that therodprovides a safety switch which is designed to .break the circuit to theelevator motor or control in the event the safety switch is tamperedwith and the housing 2'! and its enclosed rod 6| are detached.

-- A switch 69 is mounted upon the outer housing wall 43 and includes aswitch actuating plunger 19 which is resiliently urged against a plungeractuating bracket 1| on the locking arm30. The

switch 69 is of the normally open type, but in practice the switch isnormally held closedby the engagement of the plunger operating bracket1| with the switch plunger 10. In other words, when the locking arm 30is in the position shown in Figure the switch 69 is closed. However,

as soon as the locking arm 30 pivots into position to open the elevatordoors, the switch 10 is opened and the circuit to the elevator motors orcontrol is broken.

The operation of the safety switch is as follows: As the elevator carmoves into alignment with the door opening, a cam 55 engages the roller46 which pivots the lever 4| from the position shown in Figure 4 of thedrawings to the position shown in Figure 6. This action withdraws thelatch bolt 50 from the aperture 40 of the locking arm 30. However, thelocking arm 3|] remains in looking position unless the latch bar |9 ismanually operated. I

When the latch bar l9 is pulledinto retracted position, moving the latchbar to the right from the position shown in Figure 5 to the positionshown in Figure 7, the locking arm 30 pivots in a counter-clockwisedirection. A spring 12 normally biases the locking arm 30 toward theposition shown in Figure 7. Upon moving the latch bar l9 into retractedposition the angularly extending end 2|! of the bar is moved out ofalignment with the wedge shaped lug 2| so that the door l4 may belowered and the upper door I3 simultaneously raised.

As the door |4 lowers the bracket 64 moves downwardly with the door,drawing the flanged rod 60 downwardly. The flange 6| of the rod 60enters the slot 3| of the locking arm and holds this locking arm frompivotal movement. The lower end 63 of the fin or flange BI is spacedclosely above the off-set end 20 of the latch so that as soon as thelatch end 20 leaves the slot 39 the fin 6| enters the slot and holds thelocking arm 30 from pivotal movement. As long as the locking arm 30 isheld in the position shown in Figure 7, the contacts of the switch 69are open and the elevator cannot be moved.

Upon the closing of the doors l3 and M, the rod 60 is raised until it iswithdrawn from the slot 39 just as the off-set end 20 of the latch bar|9 enters the slot. When the doors are fully closed the latch bar I9 ismoved laterally into locking position as shown in Figure 5, this actionpivoting the locking arm 30 in a counter-clockwise direction. Thecontrol to the elevator motor is then in circuit and the switch contactsof switch 69 are closed.

As soon as the elevator car is moved sufiiciently to disengage theroller 46 from the cam 55 the latch bolt 50 is engaged in the lockingarm to hold the locking arm from pivotal movement. In the event theelevator passes a door opening, the lever 4| merely unlatches thelocking arm tem- 6 porarily, but relatches the same as soon as the dooropening is past.

The foregoing description applies to a con struction not employing amovable cam. In some installations, the cam 55 is movable in the shaft,and only projects into the path of the cam roller 46 when a selectedfloor is reached.

For installations of this type, the lever 4| is extended substantiallybeneath the latch bolt 50, while for fixed cam arrangements the lever 4|may be cut off just below the latch bolt 50. A switch I5 is mounted inthe elongated chamber 24, and is provided with a plunger 16 in the pathof movement of the lever 4|. When the .cam roller is out of engagementwith the movable cam 55, the lever 4| is in the position shown in Figure4 and the switch to the elevator controls or motor is closed. When thecam 55 engages the roller 46, the lever arm 4| is pivoted into theposition shown in Figure 6. In this position the latch bolt 59 isunlatched, and the switch contacts of switch 15 are opened, thuspreventing operation of the elevator.

A circuit diagram has not been shown in view of the simplicity of thecircuit, and further due to the fact that the circuits may be arrangeddi-. rectly in the elevator motor circuit or may act through suitablerelays. In the fixed cam structure, the switches 66 and 69 may be inseries so that when either is opened, the elevator cannot operate. Whena movable cam arrangement is provided, the third switch 15 may also bein series with the switches 66 and 69, and the circuit to the elevatormay be broken when any of the three switches is opened.

In accordance with the patent statutes, I have described the principlesof construction and operation of my elevator door safety lock, and whileI have endeavored to set forth the best embodiments thereof, I desire tohave it understood that obvious changes may be made within the scope ofthe following claims without departing from the spirit of my invention.

I claim:

1. A safety lock for vertically movable elevator doors having alaterally slidable latch bar having an angular extremity, the lockincluding a support, a locking arm pivotally supported by said support,a vertically grooved end in said locking bar designed to accommodate theangular extremity of said latch bar, a fixed projection engageablebeneath the extremity of said latch bar in latched position thereof, alever arm pivotally supported by said support, a roller supported by oneend of said lever arm, and a latch bolt connected to the other end ofsaid lever arm, said latch bolt being engageable with said looking armin latched position thereof for holding said locking arm from pivotalmovement and holding said latch bar in latched position from lateralmovement.

2. A safety lock for elevators having vertically movable elevator doorsand laterally movable latch bars thereupon, the lock including asupport, a locking arm pivotally supported by said support, means on thefree end of said locking arm designed to accommodate the extremity ofsaid latch bar and to be pivoted thereby, said latch bar being movablebetween two extreme positions, said bar extremity acting to pivot saidlocking arm between two extreme positions, a locking member engageablewith said latch bar extremity in one extreme position of said latch barto hold said latch bar from vertical movement, a lever pivotalllysecured to said housing,

means or pivotmg seid -lever, a liatch tort connected to said lever foraotuaition thereby, said latch bolt in *one extreme position engagingsaid locking arm when said locking "arm and said latch bar are sa'id oneextreme position.

3. The structure described :in them 32 and including means rnovezblewith theelevator door for holding :said locking arm in said otherextreme (position when said door" is at ileast partially open.

45The structure described in claim 2 and Ancluding a member fslidaiblysupported by said housing and connected to the elevator door formoeemmt'merewith, .said member engaging said docking arm in its otherextreme position and holding said locking from movement toward saidextreme position.

:5. lThe structure described in claim 12 and :in- :a control :switch:actuated *by :said locksing arm.

i6. elevator safety lock 'for use in conjunction withelevatorshaving'verticallylmovable elevator doors and laterally movablelatch barspthe lock including a supportpaslocking arm movably supported"upon said :support tor movement between two extreme xpo'sitions, saidlocking arm having (a grooved :portion designed "to Iaccommodate theextremity .of "the latch :bar, the latch bar beings-movablerbetweenitw'o extreme positions to move the locking arm togethertherewith, :an elongated :slidable :memher secured :to the door tormovement :in unison therewith, said sli'dabl'e member being supportediby said support, "means on said slidahle :meniber engageable in saidnotchedportionnf'saidilockingnrm:uponropening movement of the door forholding said locking 35 Number arm in one :extreme 'position, imeansefor holding said extremity of the eaten :bar :from *vertical movementwhen said docking varm is in its other extreme t position, and switchmeans on said :sup-

5 said support.

8. The structure described in claim i6 and mcIuding switch meansengageable with said s'lidfable means and actuated hy disengagementofisaid slidable means from said support.

10 9. The structure described in claim *6 end 11neluding to leverpivotally supplanted to said support,:.a latch bolt movable into randout 01 en- 'ga-gement with locking arm and icon d to said leverforaactuationvthereby.

.15 10. The structure described :in claim 6 and in- "cluding a cam lever:pivotally supported :by said support, a latch holtsupported :by saidsupport: and .engagea'bl'eland "disengageable with ssiid l'ookingarm,and actuated byLsaid icam 'lever.

r v0 11. The structure described in claims and in eluding a leverpivotally'secm'ed to said suppoz t, a cam roller secured to :said "leverfor actuwting the same, and a switch actuated never.

12. The structure described in claim :6 and m- 25 eluding :a leverpivotally secured to said housing,

a latch 'bolt engageable and :disengageahlewith saidlocking arm,'meansconnectingisaid latch bolt and said lever foractuationiinzunison,assecomi switch means, and means conimi'dllever dm'-adtu '30 ating said switch means.

References Cited in the file of this patent UNITED STATES PATENTS

